Generally, the invention relates to enclosures having adjustable clean gas flow environments and methods of enclosed pressure differential distribution technology. Specifically, clean gas flow enclosures, which provide for isolation of materials from airborne micro-particulate contamination.
Clean (or filtered) gas flow material handling systems are used in manufacturing to isolate clean materials from contamination by airborne macro-particulates or micro-particulates. There are three major categories of smaller filtered gas flow material handling systems, which are categorized based on the type of air flow: 1) Vertical Laminar Flow, 2) Horizontal Laminar Flow, and 3) Exhaust or Fume hoods. Each of the three types of devices have advantages depending on the various types of material handling application requirements. A focus of some of the embodiments of this invention are on the vertical laminar flow and the horizontal laminar flow categories. Particular embodiments of the invention encompass small, modular, reconfigurable, filtered gas flow environments for isolating materials from airborne particulate contamination. Smaller filtered gas flow environments are desirable because they eliminate many problems with larger clean room environments.
A significant problem with large clean room environments may be that gas must be filtered and moved long distances, while passing by people, machines, and open space. It is difficult to maintain such a gas flow and keep it within the Federal Standard 209 guidelines for particulate contamination. Federal Standard 209E, Airborne Particulate Cleanliness Classes in Cleanrooms and Clean Zones, 1992 hereby incorporated by reference. It can be even more difficult to stay within these guidelines at the work surface or within the work zone. Smaller clean air environments that move gas a shorter distance, and remove people and machines out of the airflow path are generally less costly and provide cleaner air within the work zone (or filtered gas flow space). In addition, it is much easier to direct and maintain the desired gas flow when moving air a shorter distance because the gas flow has fewer opportunities to encounter the gas currents and eddies that are produced by people moving inside a larger clean environment.
Another significant problem with clean room environments may be that it is more costly to maintain clean room environments, than a smaller, more modular clean environments. Clean rooms typically require people and machines to be totally immersed in the filtered gas flow. This requires additional space or cost for facilities and supplies. The people in clean rooms are required to wear clean room suits, shoes, gloves, masks, hair-covers, and other specialized equipment while inside the clean room environment. This also requires a changing room for people to enter and exit through and the changing room is usually accompanied by an gas-shower to blow off contamination being carried on clothing. In addition, this means that there must be aisle ways, standing or sitting areas, or the like that are part of the clean environment further adding to possible sources of contamination or adding additional cost to the clean room solution. By comparison, smaller clean environments that do not require the person to be totally immersed in the filtered gas flow can greatly reduce the need for these non-value added costs while providing a more human friendly environment to work in. See also, Adjustable Clean Air Flow Material Handling Environment, U.S. patent application 60/131,461 herein by incorporated by reference.
Even though small clean environments are desirable and generally used in manufacturing processes which require filtered gas environments, there are major problems which remain unresolved in the small clean environment industry.
A first problem can be the incompatibility of different clean environment enclosures which can be different shapes and sizes and may not be designed for being coupled or linked together. Interior and exterior dimensions vary considerably from manufacturer to manufacturer, and even between clean environment enclosures from the same manufacturer. These variations impose numerous problems with respect to material handling since even working surface heights may differ by inches, or the overall depth from one clean environment enclosure to the next may differ by several inches. In addition, even where the overall dimensions are compatible there may not be compatible side access panels on certain units which may prohibit linking units together in a side-by-side arrangement. Accommodating these variations may lead to wasted factory floor space which may not be reclaimed.
A second problem can be that existing clean enclosures do not distribute filtered gas to the entire surface of the gas flow delivery panel (or perforated plenum panel) adjoined to the clean work zone (or filtered gas flow space). In many existing arrangements the filtered gas is distributed within a static regain space of a plenum. The plenum has a perforated surface to deliver the filtered gas as a flow to the filtered gas flow space. Often the configuration of the static regain space prevents the flow of the filtered gas to distribute to the entire surface of the perforated plenum adjoined to the static regain space. As such, the filtered gas may not enter the filtered gas flow space from the entire surface area of the perforated plenum panel. This may result in only a portion of the surface of the perforated plenum panel delivering filtered gas to the filtered gas flow space. As shown for example in U.S. Pat. No. 4,927,438, the gas flow is directed substantially horizontally within a top plenum space which then delivers the gas flow substantially vertically into the filtered gas flow space. A rectangular plenum space with a dead end as shown often does not allow distribution of gas flow over the entire surface of the filter (28) or to the entire surface of the perforated plenum panel adjoining the plenum space.
A third problem can be that existing clean environment enclosures do not adjoin the perforated surface of the plenum to the entire flow path defined by the filtered gas flow space. As shown by U.S. Pat. Nos. 4,927,438; 5,326,316; and 5,487,768, the surface of the perforated plenum panels adjoined to the filtered gas flow space do not adjoin to either the entire height and width of the horizontal flow path defined by the filtered gas flow space (as disclosed by U.S. Pat. Nos. 5, 487,768 and 4,927,438), or to the entire depth and width of the vertical flow path defined by the clean work zone (as disclosed by U.S. Pat. Nos. 5,326,316 and 4,927,438).
A fourth problem can be that existing clean environment enclosures do not allow selectable gas flow within the filtered gas flow space of the clean environment enclosures. Presently, a single clean environment enclosures may not exist which allows for routine adjustment between horizontal gas flow, vertical gas flow, or a combination of both horizontal and vertical gas flow within the same filtered gas flow space. As shown by U.S. Pat. Nos. 4,557,184 and 3,895,570, the clean environment enclosures only allow for gas flow in the vertical flow path of the clean work zone.
A fifth problem can be that existing clean environment enclosures do not provide filtered gas flow having a substantially uniform velocity from the entire surface of the perforated plenum panel adjoined to the filtered gas flow space. This may be particularly true when the or filtered gas flow has a first direction of flow from the gas flow generator and a second direction of flow at the surface of the perforated plenum panel adjoined to the filtered gas flow space.
A sixth problem can be that existing clean environment enclosures do not position the area of minimum velocity in the filtered gas flow space at a location most distal from the access to the filtered gas flow space. As disclosed by U.S. Pat. No. 4,557,184, as an example, the area of lowest velocity within the clean work zone may be at the bottom rear of the filtered gas flow space. This may be the case because the enclosure only delivers filtered gas flow to the vertical flow path and the flow exits from the front access open area. The path of least resistance to gas flow (path having highest velocity) may run from the perforated plenum panel to the access open area decreasing in velocity toward the back of the enclosure as the flow arrows indicate.
A seventh problem can be that existing clean environment enclosures may not be adjusted to allow gas flow having velocity gradient substantially symmetrical about a plane which bisects the clean work zone in a diagonal fashion. As such, there may be irregular gas flow characteristics within the filtered gas flow space which may make it difficult to predict the gas flow velocity at any particular area within the filtered gas flow space. As such, the filtered gas flow within the filtered gas flow space may be unsuitable for particular applications, or may be difficult to tailor for particular applications.
An eighth problem can be that existing clean environment enclosures do not address the need for flexibility to accommodate changes in manufacturing processes and to accommodate shifts in market demand as products proceed through their life cycle. When manufacturing processes or demands change it creates demands for expanding or contracting clean space in laboratories or manufacturing facilities. These expansions and contractions typically require additional purchases of equipment (i.e. vertical or horizontal clean environment enclosures) or clean room reconstruction activities and may also require unneeded equipment to stand idle or be stored pending possible future use. Similarly, during multiple step manufacturing processes, there may be different needs for either vertical or horizontal gas flow or the combination of both depending on the product, tooling, processing requirements, and the like. As such, having flexibility in accommodating these requirements and changes with regard to clean space provides a competitive advantage for the manufacturer.
As to each of these problems and the overall desire to provide enclosures having adjustable filtered gas flow that provide enclosed pressure differential distribution technology for both larger, and for smaller versatile clean gas handling systems, the present invention provides both apparatus and methods which address each of the problems in a practical fashion.
Enclosures having adjustable filtered gas flow environments and methods of enclosed pressure differential distribution technology provide material handling substantially free from airborne particulate contamination.
The broad object of particular embodiments of the invention can be to provide class 10 to class 1,000 environments (according to Federal Standard 209E) inside an enclosed filtered gas flow space while the surrounding air quality may be class 200,000 or better.
A second broad object of particular embodiments of the invention can be to allow an operator to be external from the filtered gas flow space. Only the operator""s hands and a portion of the arms may be inside the filtered gas flow space and down stream from the material being isolated from airborne micro-particulates. This approach eliminates many of the costs and constraints of a clean room environment, including gowning areas, air showers, clean room suits, or the like. Operator comfort or ergonomics may also be addressed when the operator is external to the filtered gas flow space.
A third broad object of particular embodiments of the invention can be that the system is modular and can be easily moved and rearranged without major construction efforts or structural incompatibilities. The invention may be configured to be utilized as both a single material isolation device or in a multi-station material isolation device, utilizing multiple such modules. Additional options may be purchased to convert the system, for example, if a sealed front panel is required, the front panel and window assembly may be removed and replaced by a sealed front panel. If the sealed front panel is required, a perforated table top may allow for single pass filtered gas to exit the filtered gas flow space. The elimination of having to purchase multiple types of systems or elimination of the efforts of trying to link different brands of units together can be a major benefit of the invention which can greatly increase asset utilization.
Another broad goal of particular embodiments of the invention can be to provide vertical laminar flow, horizontal laminar flow, or a combination of both vertical laminar flow and horizontal laminar flow within the same filtered gas flow space by making routine adjustments to the enclosure. The type of gas flow selected can be based upon the type of material being handled, the process requirements, or both. The optimum airflow for any given project may be dependent upon many factors, such as the size and shape of the target object being worked upon, as well as the size and shape of the process tooling. In many, but not all, instances a combination of vertical and horizontal gas flow may be optimal. Once the decision has been made as to the type of gas flow that may be optimal, the invention allows the customer to make a few minor adjustments to the apparatus to achieve the optimal gas flow via the use of the selectable gas flow mechanisms.
Another significant object of particular embodiments of the invention can be to configure plenums which distribute filtered gas flow from the gas flow generator to the entire surface of the perforated plenum panel adjoined to the plenum space.
Another significant object of particular embodiments of the invention can be to adjoin the perforated surface of the plenum to the entire flow path (horizontal or vertical or otherwise) defined by the filtered gas flow space.
Another significant object of particular embodiments of the invention can be to deliver filtered gas flow from the perforated surface of the plenum adjoined to the gas flow space at a substantially uniform velocity.
Another significant object of particular embodiments of the invention can be to configure plenums which convert filtered gas flow from the gas flow generator having a first direction of flow to a second direction of flow at the perforated surface of the plenum adjoined to the filtered gas flow space. This object of the invention may also include the above-mentioned objects of the invention such as distributing filtered gas to the entire surface area of the perforated surface of the plenum that adjoins the plenum space, and providing substantially uniform gas velocity at the perforated surface of the plenum that adjoins the filtered gas flow space.
Another significant object of particular embodiments of the invention can be to position the filtered gas flow of lowest velocity at a location within the filtered gas flow space that is most distal from the primary access opening to the filtered gas flow space.
Another significant object of particular embodiments of the invention can be to provide a filtered gas flow within the filtered gas flow space having substantial symmetry about a plane that projects from the area of lowest velocity within the filtered gas flow space and substantially bisects the primary access opening.
Yet another object of particular embodiments of the invention can be to allow for easy room-side maintenance which reduces equipment down time. There may be easy access to the gas filters for more frequent or easier preventive maintenance. There may also be a utilities attachment panel on top of the unit that allows for easy hook-up of power and other attachments which go to the control panel or optional utility ports.
Still another object of particular embodiments of the invention can be to allow convenient material handling or material movement from one linked unit to another, into and out of the unit, from the front, side, or back. Other embodiments of the invention of may include rear access doors for material entry or exit as well as alternate types of side panels allowing for side to side material passage. Material may also be moved through the front access panel. Each unit may have a table or work surface (or bottom panel) placed within it. The design allows for custom tables, conveyor systems, standard clean room type tables, special equipment with no tables and built-in tables.